The major objectives of this study are to: 1) confirm reports that cases with onset of schizophrenia prior to 13 years of age have an increased aggregation of schizophrenia and schizophrenia spectrum personality disorders in their families as compared to cases of adult onset schizophrenia, 2) test the hypothesis that certain measures of attention/information processing (AIP) index a genetic liability to schizophrenic disorder, 3) determine if the distribution of AIP impairments amongst the first degree relatives of schizophrenic children is consistent with a simple model of genetic transmission, and 4) test the hypothesis that performance on certain AIP tasks provides a useful basis for sub-typing schizophrenic patients by determining if schizophrenic children with and without AIP impairments differ in their short term response to neuroleptic treatment, incidence of minor physical anomalies, familial aggregation of schizophrenic spectrum disorders and in ratings of formal thought disorder and the frequency of parental communication deviance. Seventy five families in each of three groups will be studied: 1) families with a schizophrenic child, 2) families with an attention deficit disorder child, and 3) families with children who have no history of psychiatric disorder. Children with an attention deficit disorder provide a test of the diagnostic specificity of the above relations. Proband will be diagnosed with a structured diagnostic interview and rated on a measure of formal thought disorder. AIP performance will be evaluated and minor physical anomalies measured in all proband and their first degree relatives. First degree relatives will be administered structured diagnostic interviews to make DSM III axis I diagnoses and diagnoses of schizophrenic spectrum personality disorders, and psychometric measures of psychosis proneness. Family history of schizophrenic disorders will be determined for second and third degree relatives. All assessments of first degree relatives will be conducted by staff blind to the proband's diagnosis.